The stabilization of expansive soil using sugarcane straw ash (Bagasse ash) and lime

Expansive soils pose significant challenges to civil engineering projects due to their high moisture-induced volume changes, resulting in detrimental effects on foundations, structures, and infrastructure. This study investigates the effectiveness of utilizing bagasse ash and lime (calcium hydroxide) as stabilizers for expansive soil. Bagasse ash (BA) is an abundant industrial waste from the sugar production industry and is an active pozzolan. The geotechnical characteristics of the expansive soil (control sample) were identified as clayey sand, containing an appreciable amount of organic and inorganic silts and clays. The ratios for investigation consisted of various lime and bagasse ash (2%, 4.5%, and 7%) at a ratio of 1:3, respectively. The maximum dry density and optimum moisture content of the control sample were calculated as 12.91 kN/m³ and 30%, respectively, and were consistent with values observed in similar studies. Increasing stabilizer contents resulted in a decrease in density across all ratios. Free swell and Atterberg’s results displayed that the 7%L-21%BA was the most effective ratio at reducing the swelling potential of the control soil. The CBR value of the control sample was 5.22% and indicated that in its current state, it would not be suitable for road subgrade applications, as they require at least 10%. With the addition of 7%L and 7%L-21%BA admixture, the CBR values increased to 19.17% and 17.12%, respectively. Furthermore, the addition of 7%L and 7%L-21%BA to the soil greatly reduced cohesion by 78.6% and 65.8%, respectively. However, it increased the internal friction angle by 32.9% and 46.9%, thus increasing its shear strength and bearing capacity.